2-hydroxynaphthalene-8-monosulfo-6-carboxylic acid and process of making it



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NEAR FEANKFORT-ON-THE-MAIN, GERMANY, AS-

SIGNOR '10 GENERAL ANILINE WORKS, INC., NEW YORK, N. Y., A CORPORATION OF DELAWARE @HYDBOXYNAPHTHALENE-SrMdNOSULFO-G-CARBOXYLIC ACID AND PROCESS OF MAKING. IT

No Drawing. Application filed March 26, 1928, Serial No. 264,977,

My invention relates to a new Q-hydroxynaphthalene 6 carboxymonosulfonic acid having probably the formula:

HOaS

which acid is obtained by acting with concentrated sulfuric acid advantageously at temperatures ranging from 50 to 80 and separating the plurality thus formed by taking advantage of the dif- Jreyent solubility of their neutral alkali metal sa its.

The new 2-hydroxynaphthalene-8-sulto-6- carboxylic acid is when dry a colorless powder, it does not combine in a dilute sodium carbonate solution with diazocompounds of a low capacity for combining, such as diazotized aniline or diazotized para-toluidine, it"

is characterized by a strong blue fluorescence of its solutions in strong sodium carbonate Then the mixture 1s stirred for some hours while slowly increasing the temperature to 80. The mass is poured on ice and the acid sodium salts of the formed sulfomc acids are separated by adding common salt, then the mixture of these salts is converted into the corresponding neutral salts by treatment with sodium car onate and the neutral solution therefrom is evaporated until a crystalline separation begins. After cooling down the neutral disodium salt of 50. 2 hydroxynaphthalene 3 monosulfo-fi-car of monosulfonic acids slowly intro- 7,

and in Germany March 30, 1927.

boxylic acid separates almost entirely in compact needles. From the filtrate the 2-hydroxynaphthalene-8-monosulfo 6 carboxylic acid may be obtained by adding hydrochloric acid.

I claim:

1. As a new compound a 2-hydroxynaphthalene-6-carboxy-monosulfonic acid having probably the formula:

' Hots HOOO which acid is when dry a colorless powder, which does not combine in a dilute sodium carbonate solution with diazocompounds of a low capacity for combining, which is characterized by a strong blue fluorescence of its solutions in stron sodium carbonate solutie and its spairmgly soluble acid magne- "sium salt, the acid sodium salt of which crystallizes in fine needles from hot water.

2. A process for producing a new 2-hy droxynaphthalene 6 carboxymonosulfonic acid having probably the formula:

HO: S

which process comprises acting with concentrated sulfuric acid at temperatures ranging from about 50 to 80 on 2-hydroXynaphthalene-G-carboxylic acid and separating the, 2 hydroxy naphthalene-(i'-carboxy-monosulfonic acid from the plurality of monosulfonic acids formed by taking advantage of the diffei'ent solubility oftheir neutral alkali metal sa ts.

In testimony whereof, I all-l2; my signature.

' FRIEDRICH KRECKE. 

